Polishing pad, method of polishing and polishing apparatus

ABSTRACT

A polishing pad according to the invention comprises a pad body having a polishing surface and a support surface and a plurality of hole apertures extending from the polishing surface to the support surface, each of the plurality of apertures having a noncircular shaped opening oriented at a predetermined angle with respect to a radial direction of the polishing pad.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2006-86087, filed on Mar. 27, 2006, theentire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a polishing pad, a method of polishingand a polishing apparatus for polishing a semiconductor wafer, which areused for a chemical and mechanical polishing (CMP) work in a process ofmanufacturing semiconductor devices. More particularly, the inventionrelates to a polishing pad, method of polishing and a polishingapparatus which facilitate a feed flow of a slurry liquid to thepolishing pad for a semiconductor wafer.

2. Description of the Related Art

In a process of manufacturing semiconductor devices, a CMP work iscarried out to polish and flatten dielectrics surface of a wafer. Apolishing pad is used for flattening the dielectrics surface. Apolishing surface of the polishing pad for use in the CMP work isplanar. A surface of the wafer to be polished and the polishing surfaceof the polishing pad are arranged in parallel to each other. Thus, thewafer surface and the polishing surface are arranged in contact witheach other and both are rotated for polishing. Various types ofpolishing apparatuses are used.

For example, a polishing pad 100 as shown in FIG. 19 has a flexible pad101 and a body pad 102. The body pad 102 is made of a hard material,foamed urethane, or the like. The body pad 102 has a number of throughholes or apertures, which pass through the body pad.

A polishing pad 110 as shown in FIG. 20 has a flexible pad 111, a bodypad 112, through holes 113 and lattice like polishing grooves 114. Thegrooves supply and remove an abrasive liquid or slurry and toeffectively removes a polishing waste. A polishing pad 112 havingpolishing grooves 114 formed therein has a high ability to supply andremove the abrasive liquid.

Therefore, such a pad is advantageous in that polishing amountvariations between the central part and the peripheral end part of thewafer are small. The polishing pad is advantageous in that it is easy topeel the wafer from the polishing pad since air can enter between thecenter of the wafer and the pad through the grooves.

Variety shapes of through holes are developed to supply and remove aslurry and to effectively remove a polishing waste(refer to, forexample, Jpn. Pat. Appln. KOKAI Publication No. 2004-71985 and Jpn. Pat.Appln. KOKAI Publication No. 2003-300149).

However, this type of polishing pad suffers from the following problems.A pad body 102 which has only through holes 103 is not easy to bringforward to feed liquid. On the other hand, a pad body 112 which has onlypolishing grooves 114 can bring forward to feed liquid into a wafer.However, the depth of the polishing grooves 114 is shorter than thedepth of through holes 103. Therefore, the polishing pad with the padbody 112 is short life.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a polishing padwhich can polish a wafer evenly with small variations of polishingamount. It is an object of the present invention to provide a method ofpolishing which can polish a wafer evenly with small variations ofpolishing amount. It is an object of the present invention to provide apolishing apparatus which can polish a wafer evenly with smallvariations polishing amount.

-   (1)According to one embodiment of the present invention, a polishing    pad for polishing an object including a pad body having a polishing    surface and a support surface and a plurality of hole apertures    extending from the polishing surface to the support surface, each of    the plurality of apertures having a noncircular shaped opening    oriented at a predetermined angle with respect to a radial direction    of the polishing pad.-   (2) According to another embodiment of the present invention, a    polishing apparatus for polishing an object including a holder    mechanism configured to hold the object, a polishing pad configured    to be arranged to face the be-polished object hold by the holder    mechanism, the polishing pad including a plate-like pad having a    polishing surface and a support surface, a drive mechanism to rotate    the polishing pad a plurality of hole apertures extending from the    polishing surface to the support surface, each of the plurality of    apertures having a noncircular shaped opening oriented at a    predetermined angle with respect to a radial direction of the    polishing pad.-   (3) According to another embodiment of the present invention, a    method of polishing an object including holding the object and    pressing a polishing pad in contact with the object rotating the    polishing pad, the polishing pad including a pad body having a    polishing surface and a support surface and a plurality of hole    apertures extending from the polishing surface to the support    surface, each of the plurality of apertures having a noncircular    shaped opening oriented at a predetermined angle with respect to a    radial direction of the polishing pad.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate exemplary embodiments of theinvention, and together with the general description given above and thedetailed description of the embodiments given below, serve to explainthe principles of the invention.

FIG. 1 is a schematic view of a polishing apparatus having a polishingpad in accordance with one embodiment of the invention.

FIG. 2 is a plan view showing the polishing pad in accordance with oneembodiment of the invention.

FIG. 3 is a plan view showing through holes of the polishing pad inaccordance with one embodiment of the invention.

FIG. 4 is a graph showing a relationship between the polishing rate andthe proportion of major axis of the through hole in accordance with oneembodiment of the invention.

FIG. 5 is a plan view showing a polishing pad in accordance with anotherembodiment of the invention.

FIG. 6 is an explanatory view showing positional relation of the throughhole in FIG. 5

FIG. 7 is an explanatory view showing relation of polishing rate inaccordance with another embodiment of the invention.

FIG. 8 is a plan view showing a polishing pad in accordance with anotherembodiment of the invention.

FIG. 9 is an explanatory view showing positional relation of the throughhole in FIG. 8.

FIG. 10 is an explanatory view showing a relation of polishing rate anda proportion of major axis to minor axis of the through hole inaccordance with another embodiment of the invention.

FIG. 11 is a plan view showing a polishing pad in accordance withanother embodiment of the invention.

FIG. 12 is a plan view showing a polishing pad in accordance withanother embodiment of the invention.

FIG. 13 is an explanatory view showing positional relation of a throughhole and a central of the polishing pad in accordance with anotherembodiment of the invention.

FIG. 14 is an explanatory view showing relation of polishing rate andangle in accordance with another embodiment of the invention.

FIG. 15 is a plan view showing a polishing pad in accordance withanother embodiment of the invention.

FIG. 16 is a plan view showing a polishing pad in accordance withanother embodiment of the invention.

FIG. 17 is an explanatory view showing positional relation of a throughhole and a central of the polishing pad in accordance with anotherembodiment of the invention.

FIG. 18 is a plan view showing a polishing pad in accordance withanother embodiment of the invention.

FIG. 19 is a cross sectional view showing a polishing pad.

FIG. 20 is a cross sectional view showing a polishing pad.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a structural view showing a polishing apparatus 100 set up apolishing pad 10, which is a first embodiment of the present invention.FIG. 2 is a plan view showing the polishing pad 10. FIG. 3 is a planview showing through holes 20 which is provided on the polishing pad 10.X is a rotating center on the polishing pad 10, F is a flowing directionof abrasive liquid and P is a rotating direction of the polishing pad10.

The polishing apparatus 100 has the polishing pad 10, a holder mechanism110 providing a wafer w and a rotary drive mechanism 120 which rotatesthe polishing pad 10, as shown in FIG. 1.

The polishing pad 10 is laminated with a soft pad 11 and a pad body 12.The pad body 12 is made of hard resin such as formed polyurethane orurethane.

The pad body 12 is provided with the through holes 20. The through holes20 are provided from a polishing surface 12 a to a support surface 12 b,in other words, in the thickness direction of the pad body 12. Thethrough holes 20 formed by such as a punching process or a nestingblock.

A predetermined number of the through holes 20 are provided inapproximately a concentric fashion on the polishing body 12, as shown inthe embodiment illustrated in FIG. 2. The through holes 20 is providedin approximately a concentric fashion with respect to the rotatingcenter X on the polishing pad 10 when a to-be-polished object ispolished, too. The through holes 20 are noncircular shaped openings. Thethrough holes 20 are provided in a predetermined angle with respect to aradial direction. It is better that all of the through holes 20 areprovided in the same predetermined angle. However, if there is apositive effect, all of the through holes 20 don't need to be sameangle.

The through holes 20 may be elliptical, as shown in FIG. 3. Theelliptical shape of the holes has a minor axis a and a major axis b. Therotating center X is provided on a line extending from the minor axis.

In one embodiment, the through holes 20 may be provided at 1-10 per 1cm2. One of a dimension of the through holes 20 is 1-6 mm2. A surfaceratio of the through holes 20 with respect to the surface area of thepad body 12 may be 1-60 percent.

The through holes 20 are provided along a line on which the abrasiveliquid flows or travels. It is easy to flow out abrasive liquid which isin the through holes 20. As a result, it promotes to feed and exhaustthe abrasive liquid, and a polishing rate rises. And a life of thepolishing pad 10 does not change compared with a life of using onlyprior through holes.

A polishing rate rises to increase b/a (a rate of major axis for a minoraxis), as shown in FIG. 4. For example, in case of b/a=1.2, a polishingrate rises about 10 percent compared with prior through holes (b/a=1).

According to the embodiment of the polishing pad 10, it can promote tofeed and exhaust the abrasive liquid. And the polishing rate can rise.

FIG. 5 is a plan view showing a polishing pad 10A which is a secondembodiment of the present invention. FIG. 6 is a showing relationshipbetween the through holes 20 and the rotating center X. In FIG. 5 andFIG. 6, the same functional parts showing in FIG. 2 and FIG. 3 are giventhe same number and overlapping explanation is skipped.

For the polishing pad 10A, which is one embodiment of the presentinvention, the major axis of the through holes 20 is provided at apredetermined angle θ with respect to the radial direction R. Thethrough holes 20 can promote to feed and exhaust the abrasive liquidwith centrifugal force.

FIG. 7 shows a change in polishing rate when angle θ is changed from 0degree to 90 degree. When angle θ is 90 degree in FIG. 2, the minordirection is accorded with the diameter direction R. When angle θ isfrom 40 degree to 80 degree, the polishing rate is maximum. The maximumpolishing rate is twice as the polishing rate in FIG. 2. Angle θ of themaximum polishing rate change according to rotary speed of a polishingpad.

The polishing pad 10A can promote to feed and exhaust the abrasiveliquid and improve the polishing rate.

FIG. 8 is a plan view showing a polishing pad 10B which is a thirdembodiment of the present invention. FIG. 9 shows relationship betweenthe through holes 30 and the rotating center X of the polishing pad 10B.In FIG. 8 and FIG. 9, the same functional parts showing in FIG. 2 andFIG. 3 are given the same number and overlapping explanation is skipped.

On the polishing pad 10B of the embodiment of the present invention, thethrough holes 30 are provided. The through holes 30 are teardrop shapewhich shape is wider down stream area than up stream side.

A polishing rate rises to increase d/c (a rate of major axis for a minoraxis), as shown in FIG. 10. For example, in case of d/c=1.2, a polishingrate rises about 5 percent compared with prior through holes (b/a=1).

FIG. 11 is a plan view showing a polishing pad 10C which is a forthembodiment of the present invention. In FIG. 11, the same functionalparts showing in FIG. 8 are given the same number and overlappingexplanation is skipped.

On the polishing pad 10C of the embodiment of the present invention, adown stream side of the through holes 30 is angled outwardly, away fromthe center of the pad. In this arrangement, the through holes 30 canpromote to supply and drain the abrasive liquid by a centrifugal force.

FIG. 12 is a plan view showing a polishing pad 10D which is a fifthembodiment of the present invention. FIG. 13 shows relationship betweenthe through holes 40 and the rotating center X of the polishing pad 10B.In FIG. 12 and FIG. 13, the same functional parts showing in FIG. 2 andFIG. 3 are given the same number and overlapping explanation is skipped.

On the polishing pad 10D of the embodiment of the present invention,through holes 40 are provided. The through holes 40 are teardrop shapewhich shape is gradually wider down stream area than up stream side.Down stream area of through holes 40 are provided to be leaned φ degreeto inner circumference configuration.

As shown in FIG. 14, a polishing rate rises to adjust φ degree. Forexample, when φ is provided more than 20 degree, a polishing rate risesabout 5 percent compared with through holes 30 which are teardrop shape.

FIG. 15 is a plan view showing a polishing pad 10E which is a sixthembodiment of the present invention. In FIG. 15, the same functionalparts showing in FIG. 12 are given the same number and overlappingexplanation is skipped.

On the polishing pad 10E of the embodiment of the present invention, thethrough holes 40 are provided to be leaned for circumferentialdirection. In other words, a down stream area of the abrasive liquid, aside of the through holes 30 provided to be out side direction on thepolishing pad 10E.

The through holes 40 can nurture to feed and exhaust the abrasive liquidwith centrifugal force.

FIG. 16 is a plan view showing a polishing pad 10F which is a seventhembodiment of the present invention. FIG. 17 is a showing relationshipbetween the through holes 50 and the rotating center X of the polishingpad 10B.

In FIG. 16 and FIG. 17, the same reference numeral as in FIG. 2 and 3are used for the same functional parts, and their explanations areomitted.

On the polishing pad 10F of the embodiment of the present invention, thethrough holes 50 are provided. The through holes 50 are teardrop shapehaving a down stream area gradually wider than an up stream side. Downstream area of through holes 50 is angled outwardly at φ degree withrespect to the up stream side. Outer configuration is defined as belowzero.

A polishing rate rises to adjust φ degree. For example, when φ isprovided more than −20 degree, a polishing rate rises about 5 percentcompared with through holes 30 which are teardrop shape.

FIG. 18 is a plan view showing a polishing pad 10G which is a eighthembodiment of the present invention.

In FIG. 18, the same functional parts showing in FIG. 16 are given thesame number and overlapping explanation is skipped.

In one embodiment, for the polishing pad 10G, the through holes 50 areprovided to be leaned for circumferential direction. In other words, thethrough holes 50 are provided to be leaned to out side direction on downstream area of the abrasive liquid. The through holes 50 can nurture tofeed and exhaust the abrasive liquid with centrifugal force.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A polishing pad for polishing an object, comprising: a pad bodyhaving a polishing surface and a support surface; and a plurality ofhole apertures extending from the polishing surface to the supportsurface, each of the plurality of apertures having a noncircular shapedopening oriented at a predetermined angle with respect to a radialdirection of the polishing pad.
 2. The polishing pad according to claim1, wherein the opening has an elliptical shape.
 3. The polishing padaccording to claim 1, wherein the opening includes a part having agradually widening width in a predetermined direction with respect tothe radial direction.
 4. The polishing pad according to claim 2, whereinthe opening has a major axis thereof angled with respect to the radialdirection.
 5. The polishing pad according to claim 3, wherein theopening has a major axis thereof angled with respect to the radialdirection.
 6. The polishing pad according to claim 1, wherein theopening includes a part having a gradually widening width in apredetermined direction with respect to the radial direction, theopening having a down stream side curving inwardly.
 7. The polishing padaccording to claim 1, wherein the opening includes a part having agradually widening width in a predetermined direction with respect tothe radial direction, the opening having a down stream side curvingoutwardly.
 8. The polishing pad according to claim 6, wherein theopening has a major axis thereof angled with respect to the radialdirection.
 9. The polishing pad according to claim 2, wherein theopening has a major axis thereof angled with respect to the radialdirection.
 10. a polishing pad configured to be arranged to face thebe-polished object hold by the holder mechanism, the polishing padincluding a plate-like pad having a polishing surface and a supportsurface; a drive mechanism to rotate the polishing pad; a plurality ofhole apertures extending from the polishing surface to the supportsurface, each of the plurality of apertures having a noncircular shapedopening oriented at a predetermined angle with respect to a radialdirection of the polishing pad.
 11. The polishing apparatus according toclaim 10, wherein the opening has an elliptical shape.
 12. The polishingapparatus according to claim 10, wherein the opening includes a parthaving a gradually widening width in a predetermined direction withrespect to the radial direction.
 13. The polishing apparatus accordingto claim 11, wherein the opening has a major axis thereof angled withrespect to the radial direction.
 14. A method of polishing an object,comprising: holding the object; and pressing a polishing pad in contactwith the object; the polishing pad including a pad body having apolishing surface and a support surface; and a plurality of holeapertures extending from the polishing surface to the support surface,each of the plurality of apertures having a noncircular shaped openingoriented at a predetermined angle with respect to a radial direction ofthe polishing pad.
 15. The polishing method according to claim 14,wherein the opening has an elliptical shape.
 16. The polishing methodaccording to claim 14, wherein the opening includes a part having agradually widening width in a predetermined direction with respect tothe radial direction.
 17. The polishing method according to claim 16,wherein the opening has a major axis thereof angled with respect to theradial direction.